Micro-gap vacuum-assisted high-efficiency cleaning system

Abstract

The application discloses a kind of micro-gap vacuum auxiliary high-efficiency cleaning systems, it is related to the field of semiconductor manufacturing and advanced packaging technology.The system includes airtight cleaning chamber, setting in cleaning chamber and can rotate around horizontal axis platform, with the vacuum system of communication of cleaning chamber, liquid supply system and liquid discharge system, and with the control system of each system connection preceding described each system.Control system controls each system to execute cleaning cycle: vacuum system is extracted to the vacuum of cleaning chamber and establishes negative pressure environment, liquid supply system under negative pressure environment introduces cleaning liquid into cleaning chamber, platform rotates at first rotational speed and makes wafer soak in liquid, and liquid discharge system is discharged after the pressure of chamber rises Liquid.The semiconductor wafer carried by platform is placed in vertical or approximately vertical state.The application utilizes negative pressure environment to make cleaning liquid enter micro-gap inside, promotes liquid replacement by platform rotation, and can be used for the cleaning operation of chip stacking, through-hole of silicon, through-hole of glass and other structures in 3D packaging.

Description

Technical Field

[0001] This invention relates to the fields of semiconductor manufacturing and advanced packaging technology, specifically to a cleaning system for micron / submicron level gap structures in 3D integrated circuit packaging, particularly suitable for removing residual contaminants in chip stacking, through-silicon vias (TSVs), through-glass vias (TGVs), and wafer-level packaging (WLP). Background Technology

[0002] In the post-Moore's Law era, driven by advanced packaging in semiconductor manufacturing, 2.5D / 3D chip stacking, through-silicon vias (TSVs), through-glass vias (TGVs), wafer-level packaging (WLP), and high-bandwidth memory (HBM) have become core technological paths for improving integration density and computing power. These architectures generally introduce micron / submicron level, high aspect ratio (up to 10:1 and above), and ultra-high density micro-gap structures, such as interlayer gaps of 20μm or less between HBM stacked chips, deep hole walls of TSVs / TGVs, redistribution layers (RDLs), and gaps around microbumps. After etching, electroplating, bonding, and ball-mounting processes, flux, photoresist residues, metal ions, particulate contaminants, and chemical waste can easily remain in these micro-gap structures. These residues need to be removed through cleaning processes; otherwise, they will directly lead to problems such as interconnect short circuits, insulation failure, insufficient bonding strength, and accelerated electromigration.

[0003] Current cleaning methods for semiconductor micro / nano structures primarily rely on traditional processes such as atmospheric pressure immersion, spraying, spin washing, ultrasonic cleaning, and isopropyl alcohol (IPA) displacement drying. However, these processes have the following shortcomings when dealing with the high aspect ratio micro-gap structures in advanced packaging: First, under normal pressure, the cleaning fluid is prone to forming air blockage inside the micro gaps. For narrow gaps of 20μm and below and the bottom of deep holes, the cleaning fluid has difficulty penetrating. The air trapped inside the gap forms a physical barrier, and the cleaning fluid can only cover the wafer surface and cannot reach the contaminant position at the bottom of the gap, resulting in a cleaning blind zone.

[0004] Secondly, after the cleaning fluid enters the micro-gap, the solid-liquid contact area increases, and the capillary force is enhanced, making it easy for the liquid to be confined within the narrow gap. Subsequent atmospheric pressure drying, spin washing, or nitrogen purging cannot overcome the capillary and viscous forces. The contaminants dissolved in the residual liquid film during evaporation will re-precipitate, forming secondary contamination such as watermarks, salt crystals, or particle adhesion, posing a corrosion risk to copper interconnects and micro-bump structures.

[0005] Third, existing cleaning equipment has relatively limited functionality. Atmospheric pressure spray or spin cleaning equipment can only treat the wafer surface, with limited penetration capability into closed or semi-closed micro-gaps. When ultrasonic cleaning equipment is used alone, if it is placed in a different station from the spin or spray function, the wafer needs to be transferred between different devices, which not only increases process time but also introduces additional contamination risks. Vacuum-assisted technology is currently mainly used in the drying process and has not yet been integrated with the cleaning process.

[0006] Therefore, there is a need for a cleaning system that can complete deep cleaning and drying of micro-gap in one device to solve the problems of difficult penetration of cleaning fluid and drying residue in micro-gap. Summary of the Invention

[0007] The purpose of this invention is to provide a micro-gap vacuum-assisted high-efficiency cleaning system to solve the technical problem that existing cleaning equipment is unable to effectively clean and dry the micron / submicron gap structure of semiconductor wafers.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A micro-gap vacuum-assisted high-efficiency cleaning system, comprising: A sealed cleaning chamber for holding at least one semiconductor wafer; A stage is disposed in the cleaning chamber for supporting the semiconductor wafer. The stage is connected to a driving mechanism for driving the stage to rotate about a horizontal axis. A vacuum system, connected to the cleaning chamber, is used to evacuate the cleaning chamber to establish a negative pressure environment; A liquid supply system, connected to the cleaning chamber, is used to introduce cleaning liquid into the cleaning chamber; A drainage system, connected to the cleaning chamber, is used to drain the cleaning liquid from the cleaning chamber; And a control system connected to the vacuum system, the liquid supply system, the liquid discharge system and the drive mechanism, the control system being configured to control the vacuum system, the liquid supply system, the liquid discharge system and the drive mechanism to perform at least one cleaning cycle; The cleaning cycle includes: The vacuum system evacuates the cleaning chamber to create a negative pressure environment. The liquid supply system introduces cleaning liquid into the cleaning chamber under the negative pressure environment; The drive mechanism drives the platform to rotate at a first speed. The drainage system discharges the cleaning liquid after the pressure in the cleaning chamber increases.

[0009] In a further technical solution, the stage has a wafer bearing surface, which is arranged along the vertical direction, or the angle between the wafer bearing surface and the vertical direction is 0~20°.

[0010] In a further technical solution, the driving mechanism includes a drive motor and a transmission shaft. The drive motor is located outside the cleaning chamber, and the transmission shaft passes through the wall of the cleaning chamber and is connected to the platform. A sealing element is provided between the transmission shaft and the wall of the cleaning chamber.

[0011] In a further technical solution, the vacuum system includes a vacuum pump and a pressure regulating valve. The vacuum pump is connected to the cleaning chamber via a pipeline, and the pressure regulating valve is located on the pipeline to regulate the vacuum level in the cleaning chamber.

[0012] In a further technical solution, the liquid supply system includes a liquid storage tank, a liquid inlet pipeline, and a valve installed on the liquid inlet pipeline. The liquid storage tank is connected to the cleaning chamber through the liquid inlet pipeline, and the valve is used to control the opening and closing of the liquid inlet pipeline.

[0013] In a further technical solution, the liquid supply system also includes a degassing device, which is installed on the pipeline between the liquid storage tank and the cleaning chamber, and is used to perform vacuum degassing treatment on the cleaning liquid.

[0014] In a further technical solution, the liquid supply system also includes a heating device, which is installed in the liquid storage tank and is used to heat the cleaning liquid in the liquid storage tank.

[0015] A further technical solution also includes a spraying assembly disposed within the cleaning chamber for spraying cleaning liquid onto the semiconductor wafer supported on the stage.

[0016] In a further technical solution, the liquid supply system includes a first liquid supply unit and a second liquid supply unit. The first liquid supply unit is used to store and supply a first cleaning liquid to the cleaning chamber, and the second liquid supply unit is used to store and supply a second cleaning liquid to the cleaning chamber. The control system is configured to control the first liquid supply unit and the second liquid supply unit to supply cleaning liquid to the cleaning chamber in sequence.

[0017] A further technical solution also includes a heating system, which is disposed in the cleaning chamber and used to heat the interior of the cleaning chamber.

[0018] A further technical solution also includes a nitrogen supply system, which is connected to the cleaning chamber and is used to fill the cleaning chamber with nitrogen.

[0019] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0020] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0021] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0022] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing this case.

[0023] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0024] Compared with the prior art, the present invention has the following beneficial effects: 1. Regarding the penetration effect of cleaning fluid in micro-gap spaces This invention establishes a negative pressure environment within the cleaning chamber, lowering the internal air pressure compared to atmospheric pressure. Under these conditions, air trapped within the wafer's micro-gap escapes due to the pressure difference, releasing the space within the gap. When the liquid supply system introduces cleaning liquid under this negative pressure environment, the liquid enters the micro-gap under the pressure difference, reaching the contaminants at the bottom of the gap. Compared to atmospheric pressure conditions where the cleaning liquid only covers the wafer surface, this approach helps reduce cleaning blind spots within the micro-gap.

[0025] The stage rotates around a horizontal axis, and the wafer support surface is positioned vertically or at an angle of 0-20° to the vertical direction. This allows the liquid to flow along the wafer surface during entry into the cleaning solution and rotation. The opening direction of the micro-gap forms an angle with the liquid flow direction, facilitating liquid entry into the gap and the expulsion of internal gas. Negative pressure establishment, liquid introduction, and rotational immersion are all completed within a single chamber, avoiding wafer transfer between different devices and reducing the possibility of air re-trapping in the micro-gap during transfer.

[0026] The vacuum system uses a vacuum pump in conjunction with a pressure regulating valve, which can adjust the vacuum level in the chamber according to the micro-gap complexity of the wafer to be cleaned, so that cleaning operations for products of different specifications can be completed in the same equipment.

[0027] 2. Regarding the replacement and uniformity of liquid contact during the cleaning process During the cleaning process, the stage rotates at a primary speed, causing the wafer to move continuously in the liquid. As the wafer rotates, its various regions sequentially enter the liquid and generate relative motion, facilitating the exchange of liquid between the wafer surface and the surrounding liquid within the micro-gaps. Dissolved or suspended contaminants within the micro-gaps are carried out of the gaps by the liquid, while fresh cleaning liquid from the outside enters, helping to maintain a low concentration of contaminants in the liquid within the gaps and thus improving the efficiency of contaminant diffusion from the inside of the gaps to the outside.

[0028] The spray assembly allows the wafer to receive liquid spraying from the assembly while it is being rotated and immersed. The sprayed liquid flows and impacts as it lands on the wafer surface, helping to break down the liquid boundary layer on the wafer surface and at the micro-gap openings, thus promoting liquid renewal between the wafer surface and the micro-gap. Rotational immersion and spraying occur simultaneously within the same chamber, eliminating the need to transfer the wafer to other workstations.

[0029] 3. Regarding the pretreatment effect of the cleaning liquid The degassing device in the liquid supply system removes dissolved gases from the cleaning liquid before it enters the cleaning chamber, reducing the likelihood of gas bubbles precipitating due to pressure drop after the liquid enters the vacuum environment, thus helping to maintain a stable vacuum level within the cleaning chamber. The heating device controls the temperature of the cleaning liquid, ensuring it is within a preset temperature range upon entering the chamber, which helps maintain the activity of the chemical components in the cleaning liquid.

[0030] 4. The step-by-step cleaning effect of different types of cleaning solutions The arrangement of the first and second cleaning units in the liquid supply system allows the cleaning system to sequentially process the wafer using different cleaning liquids within the same chamber. The cleaning liquid supplied by the first unit is used to remove photoresist residue, metal ions, and particulate contaminants from the micro-gap, while the cleaning liquid supplied by the second unit is used to displace residual chemicals and dissolved contaminants from the wafer surface. With the two cleaning liquids supplied sequentially, after the chemical solution has removed contaminants, deionized water carries the chemical solution and its associated contaminants out of the micro-gap, effectively reducing secondary contamination caused by residual chemicals within the micro-gap.

[0031] 5. Regarding the drying effect after cleaning The heating and nitrogen supply systems allow wafers to be dried within the same chamber after cleaning without needing to be transferred to other equipment. When the vacuum system evacuates the chamber, the pressure decreases, lowering the boiling point of the residual liquid, causing it to vaporize at a lower temperature. The heating system provides heat to the chamber, accelerating the vaporization process. The nitrogen supply system fills the chamber with nitrogen, which flows through the chamber and carries away the vaporized water vapor.

[0032] During the drying process described above, when the stage rotates at a second speed higher than the first speed during the cleaning stage, centrifugal force acts on the residual liquid on the wafer surface and in the micro-gap, causing the liquid to move towards the wafer edge and detach from the wafer surface under the action of centrifugal force. The combined use of vacuuming, heating, high-speed rotation, and nitrogen filling works together from different aspects to remove the residual liquid: vacuum lowers the boiling point of the liquid and increases the pressure difference across the liquid surface; heat provides the energy required for vaporization; centrifugal force provides the driving force for the liquid to move along the wafer surface; and nitrogen flow carries the vaporized water vapor out of the chamber. The cooperation of these methods helps to reduce the re-precipitation of solutes during the evaporation of residual liquid in the micro-gap, which could lead to the formation of watermarks or salt crystals.

[0033] 6. Regarding the protective effect on wafer structures This invention introduces the cleaning liquid by creating a negative pressure environment using a vacuum system, avoiding the direct impact of high-pressure jetting on the wafer surface and microstructure. The stage rotates at a relatively low speed, ensuring more uniform force on the wafer within the liquid. The drive motor is positioned outside the cleaning chamber, preventing the heat and electromagnetic fields generated during motor operation from affecting the cleaning environment and reducing the number of electrical components requiring sealing within the chamber. These features, while achieving the cleaning objective, help reduce the risk of damage to thin wafers, fine-pitch copper pillars, and fragile microstructures.

[0034] 7. The coordination relationship between the components The aforementioned components work together in the application: the negative pressure environment provides the driving force for the cleaning liquid to enter the micro-gap, and also provides low-pressure conditions for the vaporization of residual liquid in the subsequent drying step; the rotation of the stage is used for liquid replacement in the cleaning stage and for centrifugal drainage in the drying stage, with the same drive mechanism performing different functions in different stages; multiple liquid supply units of the liquid supply system supply different liquids sequentially under the timing control of the control system, and the supply sequence of each liquid matches the cleaning process requirements; the heating system and nitrogen supply system intervene after cleaning, working with the vacuum system to complete the drying operation. With the cleaning chamber as the center, each subsystem operates sequentially according to a set time sequence under the scheduling of the control system, forming a complete cleaning-drying workflow. Attached Figure Description

[0035] AppendixFigure 1 This is a flowchart of a method according to an embodiment of the present invention; Appendix Figure 2 This is a block diagram of a cleaning system according to an embodiment of the present invention; Appendix Figure 3 This is a schematic diagram of the cleaning chamber in the cleaning system of this invention. Appendix Figure 4 This is a schematic diagram of the principle of the first cleaning cycle in an embodiment of the present invention. Figure 1 ; Appendix Figure 5 This is a schematic diagram of the principle of the first cleaning cycle in an embodiment of the present invention. Figure 2 ; Appendix Figure 6 This is a schematic diagram of the principle of the first cleaning cycle in an embodiment of the present invention. Figure 3 ; Appendix Figure 7 This is a schematic diagram of the principle of the first cleaning cycle in an embodiment of the present invention. Figure 4 ; Appendix Figure 8 This is a schematic diagram of the principle of the first cleaning cycle in an embodiment of the present invention. Figure 5 ; Appendix Figure 9 This is a schematic diagram of the principle of the first cleaning cycle in an embodiment of the present invention. Figure 6 ; Appendix Figure 10 This is a schematic diagram of the principle of the second cleaning cycle in an embodiment of the present invention. Figure 1 ; Appendix Figure 11 This is a schematic diagram of the principle of the second cleaning cycle in an embodiment of the present invention. Figure 2 ; Appendix Figure 12 This is a schematic diagram of the principle of the second cleaning cycle in an embodiment of the present invention. Figure 3 ; Appendix Figure 13 This is a schematic diagram of the principle of the second cleaning cycle in an embodiment of the present invention. Figure 4 ; Appendix Figure 14 This is a schematic diagram of the principle of the second cleaning cycle in an embodiment of the present invention. Figure 5 ; Appendix Figure 15 This is a schematic diagram illustrating the principle of the drying step in an embodiment of the present invention. Figure 1 ; Appendix Figure 16 This is a schematic diagram illustrating the principle of the drying step in an embodiment of the present invention. Figure 2 ; Appendix Figure 17 The figures show the cleaning effect of the comparative examples and various embodiments of the present invention.

[0036] In the above attached diagram: 1. Wafer; 2. Stage; 3. Cleaning chamber; 4. Heating device; 5. Spraying assembly; 6. Cleaning solution return line; 7. Cleaning solution tank; 8. Deionized water return line; 9. Deionized water tank; 10. Heating assembly. Detailed Implementation

[0037] The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the embodiments of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0038] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0039] Figure 1 This is a flowchart of a method according to an embodiment of the present invention; Figure 2 This is a block diagram of a cleaning system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the cleaning chamber in the cleaning system of this invention. Figures 4 to 9 This is a schematic diagram illustrating the principle of each stage of the first cleaning cycle in an embodiment of the present invention; Figures 10 to 14 This is a schematic diagram illustrating the principle of each stage of the second cleaning cycle in an embodiment of the present invention; Figures 15 to 16 This is a schematic diagram illustrating the principle of the drying step in an embodiment of the present invention; Figure 17 The figures show the cleaning effect of the comparative examples and various embodiments of the present invention.

[0040] like Figure 2 and Figure 3As shown, the micro-gap vacuum-assisted high-efficiency cleaning system provided by the present invention mainly includes: a cleaning chamber 3, a stage 2, a vacuum system, a liquid supply system, a liquid drainage system, a spraying assembly 5, a heating device 4, a heating assembly 10, and a control system. The liquid supply system may include a first liquid supply unit and a second liquid supply unit. In this embodiment, the first liquid supply unit is specifically a cleaning liquid tank 7 and its related pipelines, and the second liquid supply unit is specifically a deionized water tank 9 and its related pipelines. The cleaning chamber 3 is a sealed container, forming a space inside for accommodating a semiconductor wafer 1. The stage 2 is disposed inside the cleaning chamber 3 and is used to support the semiconductor wafer 1. The stage 2 has a wafer-bearing surface, which is arranged vertically or at an angle of 0-20° to the vertical direction. In this embodiment, the horizontal tilt angle of the rotation axis of the stage 2 is 0±20°, that is, the stage 2 and the wafer 1 supported thereon form an angle of 0±20° with the vertical direction. The optimal angle range is 10~15°. At smaller angles, air bubbles are less likely to escape, while at larger angles, the resistance encountered by the wafer when entering the water increases accordingly. The stage 2 is connected to a drive mechanism, which includes a drive motor and a transmission shaft. The drive motor is located outside the cleaning chamber 3, and the transmission shaft passes through the wall of the cleaning chamber 3 and connects to the stage 2. A seal is provided between the transmission shaft and the wall of the cleaning chamber 3. The drive motor can be a servo motor or a stepper motor, used to drive the stage 2 to rotate around a horizontal axis. The stage 2 can adopt a vacuum suction cup structure with suction holes, fixing the semiconductor wafer 1 onto the stage 2 by vacuum suction.

[0041] The cleaning chamber 3 is connected to a vacuum system, which includes a vacuum pump and a pressure regulating valve. The vacuum pump is connected to the cleaning chamber 3 via a pipeline, and the pressure regulating valve is located on the pipeline to regulate the vacuum level inside the cleaning chamber 3. The cleaning chamber 3 is also connected to a liquid supply system, which introduces cleaning liquid into the cleaning chamber 3. The liquid supply system includes a storage tank (i.e., cleaning liquid tank 7 and deionized water tank 9), an inlet pipeline, and a valve located on the inlet pipeline. The storage tank is connected to the cleaning chamber 3 via the inlet pipeline, and the valve controls the opening and closing of the inlet pipeline. The liquid supply system also includes a degassing device, located on the pipeline between the storage tank and the cleaning chamber 3, used to evacuate and degas the cleaning liquid before it enters the cleaning chamber 3. The liquid supply system also includes a heating device 4, located at the storage tank, used to heat the cleaning liquid inside the storage tank.

[0042] The cleaning chamber 3 is equipped with a spraying assembly 5, which is connected to the liquid supply system and is used to spray cleaning liquid onto the semiconductor wafer 1 supported on the stage 2. The spraying assembly 5 may include one or more nozzles, with the nozzles spraying towards the surface of the wafer 1. The cleaning chamber 3 is also connected to a drainage system, which includes a drainage pipeline and a valve installed on the drainage pipeline. One end of the drainage pipeline is connected to the cleaning chamber 3, and the other end is connected to a recovery tank or a discharge port. In this embodiment, the drainage pipeline includes a cleaning liquid return pipeline 6 and a deionized water return pipeline 8. One end of the cleaning liquid return pipeline 6 is connected to the cleaning chamber 3, and the other end is connected to the cleaning liquid tank 7. One end of the deionized water return pipeline 8 is connected to the cleaning chamber 3, and the other end is connected to the deionized water tank 9, so as to realize the recovery and reuse of the cleaning liquid. The cleaning chamber 3 is also connected to a nitrogen supply system, which is connected to the cleaning chamber 3 and is used to fill the cleaning chamber 3 with nitrogen. The cleaning chamber 3 is equipped with a heating component 10. The heating component 10 can be a heating element installed inside the cleaning chamber 3 or a heating jacket installed on the outer wall of the cleaning chamber 3, used to heat the inside of the cleaning chamber 3.

[0043] The control system is communicatively connected to the vacuum system, liquid supply system, liquid drainage system, drive mechanism, spraying assembly 5, heating device 4, heating assembly 10, and nitrogen supply system to control the timing of each system's actions. The control system can be a programmable logic controller (PLC) or an industrial computer, which stores a preset control program for executing at least one cleaning cycle.

[0044] The working process of the micro-gap vacuum-assisted high-efficiency cleaning system provided by the present invention will be described in detail below with reference to specific embodiments.

[0045] In this embodiment, the semiconductor wafer 1 to be cleaned is an HBM chip stacked wafer with a 20μm inter-chip micro-gap inside.

[0046] (a) Preparation stage like Figure 2 , Figure 3 As shown, single (or multiple) HBM chip stacked wafers 1 are vertically clamped and fixed on the stage 2. When there are multiple wafers 1, they are stacked in the front-to-back direction, ensuring that the micro-gaps between each wafer 1 are exposed to the internal space of the cleaning chamber 3. The wafers 1 are adsorbed and fixed through the vacuum adsorption holes of the stage 2. Then the cleaning chamber 3 is closed, creating a sealed environment inside the cleaning chamber 3.

[0047] (ii) First cleaning cycle (potassium hydroxide cleaning) like Figure 4As shown, the potassium hydroxide (KOH) cleaning solution in the cleaning solution tank 7 is preheated by the heating device 4 to 75~85℃. Increasing the temperature of the cleaning solution helps to enhance the activity of the reagent and accelerate the removal of contaminants. However, excessively high temperatures may affect the stability of the wafer structure and change the reaction characteristics of the reagent. Therefore, it is necessary to select an appropriate temperature range based on the wafer material, reagent characteristics, and type of contaminants.

[0048] Figure 5 As shown, the control system commands the vacuum system to start, evacuating the sealed cleaning chamber 3 to -60 kPa (gauge pressure) and maintaining this vacuum for 5 minutes to establish a stable negative pressure environment inside the cleaning chamber 3. The gauge pressure of the negative pressure environment is preferably between -60 kPa and -120 kPa, with the specific value determined by the micro-gap complexity of the semiconductor wafer 1 to be cleaned; the two are positively correlated—the higher the micro-gap complexity, the higher the required vacuum level, and the lower the required negative pressure level. Simultaneously, the degassing device in the liquid supply system performs vacuum degassing on the potassium hydroxide cleaning solution in the cleaning solution tank 7 to remove dissolved gases, preventing them from precipitating out after entering the cleaning chamber 3 and affecting the vacuum level inside the chamber.

[0049] like Figure 6 As shown, the control system opens the valve on the inlet pipe, utilizing the pressure difference between the negative pressure environment inside the cleaning chamber 3 and the external liquid source to draw potassium hydroxide cleaning solution from the cleaning solution tank 7 into the cleaning chamber 3 through the inlet pipe. Driven by the pressure difference, the cleaning solution enters the cleaning chamber 3, and its liquid level gradually rises. The immersion height is greater than or equal to the rotation radius of wafer 1, meaning the liquid level must at least submerge the center point of wafer 1, ensuring that the entire area of ​​wafer 1 is in contact with the cleaning solution. During this process, the negative pressure environment inside the cleaning chamber 3 causes the air trapped inside the micro-gap of wafer 1 to escape under the pressure difference, allowing the cleaning solution to enter the micro-gap.

[0050] like Figure 7As shown, the control system commands the drive mechanism to start, driving the stage 2 to rotate along a horizontal or near-horizontal axis. The angle between the rotation axis of the stage 2 and the vertical direction is 0±20°, preferably 10~15°. The rotational speed of the stage 2 is set to a first speed, which is 5~60 rpm, and in this embodiment it is set to 30 rpm. The stage 2 drives the wafer 1 to rotate together, so that the wafer 1 is immersed in the cleaning liquid. Through rotation, on the one hand, different areas of the wafer 1 can fully contact the cleaning liquid, and on the other hand, it accelerates the replacement between the liquid inside and outside the micro-gap, ensuring the cleaning efficiency and cleaning effect of the micro-gap. At the same time, the control system activates the nitrogen supply system, injecting nitrogen into the cleaning chamber 3. The injected nitrogen can form a positive thrust, which works in conjunction with the negative pressure suction of the chamber. Relying on the bidirectional action of negative pressure suction and nitrogen push, the penetration efficiency of the cleaning liquid into the deep microstructure is improved. In addition, the injection of nitrogen can also play the following roles: First, it can slightly adjust and stabilize the vacuum level inside the cleaning chamber 3, ensuring stable cleaning conditions; second, the nitrogen bubbles, together with the rotation of wafer 1, form liquid flow disturbances, which help to break the liquid boundary layer at the micro gaps and accelerate the exchange of cleaning solution and the removal of contaminants; third, it can carry away and expel the tiny bubbles precipitated in the vacuum environment, preventing bubbles from blocking the contact between the cleaning solution and the inner wall of the micro gaps; fourth, it can create an inert atmosphere, reduce the oxygen content in the chamber, and inhibit the galvanic corrosion of the metal interconnect structure by the alkaline cleaning solution.

[0051] like Figure 8 As shown, the control system activates the spray assembly 5, spraying the outer surface of wafer 1 through nozzles. Simultaneously, the cleaning fluid return line 6 is opened, allowing the cleaning fluid in cleaning chamber 3 to return to the cleaning fluid tank 7, achieving fluid circulation. This circulating spray accelerates fluid exchange, ensuring that the high-concentration contaminant liquid displaced from the micro-gap is promptly removed, while fresh cleaning fluid continuously replenishes the micro-gap. Furthermore, the ultrasonic generator can be activated to apply ultrasonic energy to the cleaning fluid in cleaning chamber 3, enhancing the removal of contaminants from the micro-gap. While applying ultrasonic energy, the rotation of the stage 2 is stopped to avoid reducing the effectiveness of the ultrasonic waves due to turbulent water flow caused by rotation. Ultrasonic cleaning lasts for 5 minutes.

[0052] like Figure 9 As shown, after cleaning is completed, the control system shuts off the spray assembly 5 and closes the inlet valve. The air pressure in the cleaning solution tank 7 is reduced (or the internal pressure of the cleaning chamber 3 is increased), establishing a pressure difference between the cleaning chamber 3 and the cleaning solution tank 7. The potassium hydroxide cleaning solution is then discharged into the cleaning solution tank 7 via the cleaning solution return pipeline 6. The discharged cleaning solution can be reused after filtration.

[0053] (iii) Second cleaning cycle (deionized water rinsing) like Figure 10As shown, the control system instructs the vacuum system to evacuate the cleaning chamber 3 to -60 kPa again, establishing a negative pressure environment. Simultaneously, the degassing device in the liquid supply system performs vacuum degassing on the deionized water in the deionized water tank 9 to remove dissolved gases.

[0054] like Figure 11 As shown, the control system opens the valve on the inlet pipe, utilizing the pressure difference between the negative pressure environment inside the cleaning chamber 3 and the deionized water tank 9 to draw deionized water from the deionized water tank 9 into the cleaning chamber 3 through the inlet pipe. The soaking time in the deionized water is maintained for 2 minutes to ensure that the wafer 1 is thoroughly rinsed in the deionized water.

[0055] like Figure 12 As shown, the control system commands the drive mechanism to start the platform 2 to rotate, with the rotation speed set to 40 rpm. At the same time, nitrogen gas is injected into the cleaning chamber 3.

[0056] like Figure 13 As shown, the control system activates the spraying assembly 5 to spray the outside of the wafer 1, and opens the deionized water return pipeline 8 to allow the deionized water to circulate between the cleaning chamber 3 and the deionized water tank 9 for cyclic spraying and rinsing.

[0057] like Figure 14 As shown, after rinsing is completed, the spraying is stopped, the air pressure of the deionized water tank 9 is reduced (or the pressure of the cleaning chamber 3 is increased), and the deionized water is discharged into the deionized water tank 9 through the deionized water return pipe 8 through the pressure difference, or directly discharged from the system.

[0058] (iv) Drying steps like Figure 15 As shown, after all cleaning cycles are completed, the control system instructs the vacuum system to evacuate the cleaning chamber 3 to -80 kPa. The vacuum level in this drying step is greater than the vacuum level during the cleaning cycle (-60 kPa). This is because wafer 1 has high aspect ratio micro-gaps, and the vacuum level set in the cleaning process can effectively break the gap blockage, ensuring smooth penetration and discharge of the cleaning fluid; during the drying stage, only a trace amount of adsorbed residual liquid remains in the gap, which is more difficult to remove, so the drying vacuum level is not lower than the cleaning vacuum level: an equivalent vacuum level can maintain the liquid flow channel and avoid residual liquid retention; a higher vacuum level can further increase the pressure difference, lower the liquid boiling point, and enhance the extraction and vaporization of residual liquid.

[0059] Simultaneously, the control system activates the heating component 10, heating the interior of the cleaning chamber 3 to 60°C. Vacuum effectively enhances the removal of cleaning liquid from the wafer, and combined with heating, further reduces watermarks on the wafer surface.

[0060] The control system commands the drive mechanism to increase the rotation speed of the stage 2 to a second rotation speed, which is 200-900 rpm. In this embodiment, it is set to 400 rpm, which is greater than the aforementioned first rotation speed (the rotation speed during the cleaning stage). When the stage 2 rotates at the second rotation speed, centrifugal force acts on the residual liquid on the surface of wafer 1 and inside the micro-gap. On the one hand, the centrifugal force overcomes capillary attraction and viscosity, throwing the liquid from inside the gap towards the edge of the wafer, causing it to detach from the micro-gap; on the other hand, it compresses the thickness of the residual liquid in the gap from a micron-level liquid film to a nano-level thin liquid film, significantly increasing the contact area between the liquid and the vacuum and hot air, and accelerating the vaporization rate. Drying continues for 10 minutes.

[0061] like Figure 16 As shown, after the drying step has been performed for a certain period of time, the control system activates the nitrogen supply system, filling the cleaning chamber 3 with nitrogen to atmospheric pressure and maintaining this pressure for 3 minutes. The heated nitrogen is rapidly introduced into the cleaning chamber 3, which accelerates the removal of residual liquid or moisture from the micro-gaps in wafer 1, thereby increasing the drying rate. The inert atmosphere of nitrogen can isolate external moisture and prevent galvanic corrosion of the metal interconnect structure.

[0062] This completes the entire process of micro-gap vacuum-assisted high-efficiency cleaning according to the present invention.

[0063] The heating device 4, heating component 10, degassing device, ultrasonic generator, etc. involved in this invention are all existing technologies, and their specific structures and principles will not be described in detail here.

[0064] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A micro-gap vacuum-assisted high-efficiency cleaning system, characterized in that: include: A sealed cleaning chamber for holding at least one semiconductor wafer; A stage is disposed in the cleaning chamber for supporting the semiconductor wafer. The stage is connected to a driving mechanism for driving the stage to rotate about a horizontal axis. A vacuum system, connected to the cleaning chamber, is used to evacuate the cleaning chamber to establish a negative pressure environment; A liquid supply system, connected to the cleaning chamber, is used to introduce cleaning liquid into the cleaning chamber; A drainage system, connected to the cleaning chamber, is used to drain the cleaning liquid from the cleaning chamber; And a control system connected to the vacuum system, the liquid supply system, the liquid discharge system and the drive mechanism, the control system being configured to control the vacuum system, the liquid supply system, the liquid discharge system and the drive mechanism to perform at least one cleaning cycle; The cleaning cycle includes: The vacuum system evacuates the cleaning chamber to create a negative pressure environment. The liquid supply system introduces cleaning liquid into the cleaning chamber under the negative pressure environment; The drive mechanism drives the platform to rotate at a first speed. The drainage system discharges the cleaning liquid after the pressure in the cleaning chamber increases.

2. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 1, characterized in that: The stage has a wafer support surface, which is arranged along the vertical direction, or the angle between the wafer support surface and the vertical direction is 0~20°.

3. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 1, characterized in that: The driving mechanism includes a drive motor and a transmission shaft. The drive motor is located outside the cleaning chamber, and the transmission shaft passes through the wall of the cleaning chamber and is connected to the platform. A seal is provided between the transmission shaft and the wall of the cleaning chamber.

4. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 1, characterized in that: The vacuum system includes a vacuum pump and a pressure regulating valve. The vacuum pump is connected to the cleaning chamber via a pipeline, and the pressure regulating valve is located on the pipeline to regulate the vacuum level in the cleaning chamber.

5. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 1, characterized in that: The liquid supply system includes a liquid storage tank, a liquid inlet pipeline, and a valve installed on the liquid inlet pipeline. The liquid storage tank is connected to the cleaning chamber through the liquid inlet pipeline, and the valve is used to control the opening and closing of the liquid inlet pipeline.

6. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 5, characterized in that: The liquid supply system also includes a degassing device, which is installed on the pipeline between the liquid storage tank and the cleaning chamber, and is used to perform vacuum degassing on the cleaning liquid.

7. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 5, characterized in that: The liquid supply system also includes a heating device, which is installed in the liquid storage tank and is used to heat the cleaning liquid in the liquid storage tank.

8. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 1, characterized in that: It also includes a spraying assembly disposed in the cleaning chamber for spraying cleaning liquid onto the semiconductor wafer supported on the stage.

9. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 1, characterized in that: The liquid supply system includes a first liquid supply unit and a second liquid supply unit. The first liquid supply unit is used to store and supply a first cleaning liquid to the cleaning chamber, and the second liquid supply unit is used to store and supply a second cleaning liquid to the cleaning chamber. The control system is configured to control the first liquid supply unit and the second liquid supply unit to supply cleaning liquid to the cleaning chamber in sequence.

10. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 1, characterized in that: It also includes a heating system disposed in the cleaning chamber for heating the interior of the cleaning chamber.

11. The micro-gap vacuum-assisted high-efficiency cleaning system according to claim 1, characterized in that: It also includes a nitrogen supply system, which is connected to the cleaning chamber and is used to fill the cleaning chamber with nitrogen.

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